Typical Applications
DS005516-19
FIGURE 3. LM35 with Decoupling from Capacitive Load
DS005516-6
FIGURE 6. Two-Wire Remote Temperature Sensor
(Output Referred to Ground)
DS005516-20
FIGURE 4. LM35 with R-C Damper
CAPACITIVE LOADS
Like most micropower circuits, the LM35 has a limited ability
to drive heavy capacitive loads. The LM35 by itself is able to
drive 50 pf without special precautions. If heavier loads are
anticipated, it is easy to isolate or decouple the load with a
resistor; see
Figure 3.
Or you can improve the tolerance of
capacitance with a series R-C damper from output to
ground; see
Figure 4.
When the LM35 is applied with a 200Ω load resistor as
shown in
Figure 5, Figure 6
or
Figure 8
it is relatively immune
to wiring capacitance because the capacitance forms a by-
pass from ground to input, not on the output. However, as
with any linear circuit connected to wires in a hostile environ-
ment, its performance can be affected adversely by intense
electromagnetic sources such as relays, radio transmitters,
motors with arcing brushes, SCR transients, etc, as its wiring
can act as a receiving antenna and its internal junctions can
act as rectifiers. For best results in such cases, a bypass ca-
pacitor from V
IN
to ground and a series R-C damper such as
75Ω in series with 0.2 or 1 µF from output to ground are often
useful. These are shown in
Figure 13, Figure 14,
and
Figure 16.
DS005516-7
FIGURE 7. Temperature Sensor, Single Supply, −55˚ to
+150˚C
DS005516-8
FIGURE 8. Two-Wire Remote Temperature Sensor
(Output Referred to Ground)
DS005516-5
FIGURE 5. Two-Wire Remote Temperature Sensor
(Grounded Sensor)
DS005516-9
FIGURE 9. 4-To-20 mA Current Source (0˚C to +100˚C)
7
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